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Photo: Lance Barrett-Lennard

Marine Scientists Urge Federal Government to Reduce Underwater Noise in the Salish Sea

A group of 20 international marine scientists specializing in anthropogenic noise and the endangered southern resident killer whale population have come together to pen a letter to the Canadian government calling on Ottawa to produce a concrete, funded, science-based plan for reducing underwater noise pollution in the Salish Sea. Specifically, they want to see a reduction in shipping noise in the Salish Sea by at least 3 decibels in the next 10 years, with a further reduction by 10 dB in the next 30 years.

Southern Resident killer whales, also known as orcas, are listed as endangered in both Canada and the US with a population size of just 78 individuals. Finding enough food to eat, particularly Chinook salmon their preferred prey source, is a major threat to these orcas. Constant vessel noise, primarily from shipping around the busy Port of Vancouver, affects the whales’ ability to find food, navigate and communicate with each other. Read the letter below (or click here).

We, the undersigned, are marine scientists with specific expertise in the biology of the endangered southern resident population of killer whales and/or in anthropogenic ocean noise in the Salish Sea.

In several recent announcements and press statements, the Canadian government has committed to ensuring that new industrial developments do not increase underwater noise within the critical habitat of southern resident killer whales. We commend you for acknowledging the increased threat that noise from these projects presents to this critically endangered population. At the same time, we urge you to produce a concrete, funded, science-based plan and a schedule for reducing the already excessive levels of underwater noise pollution in the Salish Sea from all sources, to help enable the population’s recovery and substantially improve its acoustic habitat. It is essential that any new developments be consistent with these broader goals.

The southern residents are a distinct and iconic population of killer whales, which live much of the year in the Salish Sea off the west coast of Canada and the United States. This population has failed to recover since live-captures for aquaria stopped in the late 1970s; as of January 2017, it had only 78 members with fewer than 30 reproductive females. Numerous threats—including, most prominently, periodic prey shortages, physical and acoustic disturbance, and toxic contamination—are undermining the population’s ability to successfully recruit new calves, and are threatening its long-term survival. For these reasons, the southern resident population is listed as endangered under Canada’s Species at Risk Act and the U.S. Endangered Species Act. Virtually the entirety of the Salish Sea is recognized as critical habitat by both countries under these statutes.

The acoustic environment of the Salish Sea is already highly degraded relative to pre-industrial conditions. As a result, the southern residents are exposed to vessel noise the majority of the time they spend in their designated critical habitat, during which their communication space is significantly reduced. Vessel presence and noise exposure are associated in resident killer whales with a substantial reduction in foraging activity, limiting their food acquisition abilities. In what is already a food-compromised environment, we believe that this foraging impairment is not sustainable. Vessel noise is also likely to adversely affect the southern residents in other material ways, such as by masking and altering calls that are vital to their communication and by inducing chronic stress.

Both the Canadian and U.S. governments have recognized that acoustic disturbance of the southern resident killer whale population must be reduced. Canada’s Resident Killer Whale Recovery Strategy and subsequent Action Plan require actions to ensure that anthropogenicdisturbance does not prevent the recovery of southern and northern resident killer whales, andcall for regulations and other measures to “reduce or eliminate” their physical and acousticdisturbance. Similarly, the Recovery Plan formulated by the U.S. government requiresmanagement actions to reduce vessel disturbance and auditory masking as a criterion forrecovery and delisting.

Both governments consider vessel presence and vessel noise among the principal threats to thesurvival and recovery of the southern resident population. Increasingly, however, continuouslow-frequency noise from commercial shipping and other sources is also associated with a rangeof adverse impacts on fish and invertebrate species. Given current levels of commercial andindustrial activity, chronic anthropogenic noise represents a serious threat to the Salish Seaecosystem, of which the southern residents are an important component.

The Scientific Committee of the International Whaling Commission has repeatedlyrecommended an initial global target for the reduction of shipping noise of 3 dB (decibels)within 10 years and 10 dB within 30 years, relative to current levels. The goal is to reverse theupward trend (+3 dB/ decade) in deep-water ambient noise pollution during the second half ofthe 20th century, largely attributable to commercial shipping. We believe that an even moreprecautionary target is necessary and appropriate in areas, such as the Salish Sea, that are moreacoustically degraded and that constitute critical habitat for a noise-sensitive endangered species. As part of its management plan for the region, the Canadian government should include designand engineering solutions, mandatory ship speed limits, and other tangible noise-quietingmeasures, with a schedule for their implementation; and, to ensure that the noise reduction targetis met, it should periodically assess the effectiveness of its plan against pre-established criteria.The government should consider every means available, including regulation, to achievequantifiable improvements in the whales’ acoustic habitat.

Along with increasing food availability and minimizing the risk of contaminants, which includespetroleum spills, reducing acoustic disturbance from large vessels and other noise sources isessential to the recovery of the southern resident killer whale population. Once again, we aregreatly encouraged by the Canadian government’s promise to ensure that new developments donot increase ocean noise in the region. We also urge you to adopt a concrete, funded, sciencebasedplan and timetable for noise reductions that will substantially improve and restore theacoustic environment of the Salish Sea.